Back button test now verifies heading changes to "Geography" after
going back, AND checks for zero JIT errors. Catches real bugs:
- 129 JIT "Not callable: nil" errors during navigation (CSSX closure)
- Back button content may not update (to be verified after JIT fix)
New test: "no JIT errors during navigation" — fails with 129 errors,
correctly identifying the CSSX closure capture bug.
6 pass, 2 fail (real bugs, not test issues).
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>